Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

20 Claims. (Cl. 128-214) The present invention relates to a liquid dispenser and specifically to a mechanism for dispensing liquids for intravenous injections.

Persons injured and in a state of shock require prompt attention and a fatality may result if treatment is postponed awaiting favorable conditions for intravenous injections by means of the open or vented liquid container elevated to obtain hydrostatic pressure. Relatively minor injuries to civilians, and especially to military personnel on the field of combat, have often been fatal because the patient succumbed to shock while in transit, or when environment equally negativerto the use of the elevated container rendered intravenous injections impractical or impossible.

The primary object of my invention is, therefore, to provide a motor driven pumping mechanism for creating the fluid pressure required for intravenous injection without the need for elevating the container.

Another object is to provide such a mechanism so constructed as to insure a constant fluid pressure, nicely regulated and controlled to insure maximum safety.

A still further object of the invention is to provide mechanism having the above-described capacities, and further being of such character that it can be manipulated and put into use by relatively untrained personnel, and that it will carry out its intended functions with a minimum of attention during the injection procedure.

Ancillary objects will become apparent as the description proceeds.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

Fig. 2 is a plan view of the mechanism of Fig. 1 shown with the fluid container attached and ready for use;

Fig. 3 is a longitudinal sectional view (on an enlarged scale) taken substantially on line 3-3 of Fig. 2 and showing the details of the fluid container;

Fig. 4 is a longitudinal sectional view (on an enlarged scale) taken on line 4-4 of Fig. 2;

Fig. 5 is a longitudinal sectional view taken on line 55 of Fig. 4;

Fig. 6 is a side elevation of the mechanism of Fig. 1 on an enlarged scale; I

Fig. 7 is a transverse sectional view taken on line 7-7 of Fig. 5;

Fig. 8 is a partial sectional view similar to Fig.7 taken substantially on line 8-8 of Fig. 5,

Fig. 9 is a longitudinal sectional view taken substantially on line 99 of Fig. 7 (the motor spring having been removed); and

Fig. 10 is a fragmental sectional view taken substantially on line 10-10 of Fig. 6.

Referring more particularly to the drawings, my invention comprises a casing 10 having mounted therein motor means 11 (Fig. 4) and a plunger or push-rod 12. Motor means 11 comprises a shaft 13 projecting through one wall of casing 10 and provided with a manipulating finger-piece 14. Journalled on shaft 13 is a barrel 15. A clock-type coiled spring 16 is contained in said barrel and has one end thereof fixed to "said barrel, as at 17, and the other end thereof 'drivin'gly connected to 2,703,084 Patented Mar. 1, 1955 shaft 13 by means of a pin 18, or the like. Spring 16 is wound initially by rotating'barrel 15'relative to shaft 13. To prevent subsequent counter-rotation of said barrel, I provide a one-Way brake means,'here comprising a plurality of dogs 19 (Fig. 9). Each such dog is pivoted upon a pin 20 and is so proportioned as to be slightly longer than the distance from said pin to the periphery of barrel 15. Spring means 21 engages the dog to urge its free end into contact with said barrel periphery whereby a wedging action results, permitting rotation of said barrel in one direction only. I Obviously, other types of holding devices for said barrel could be employed, such as set screws, or the like.

Push-rod 12 is reciprocably mounted in casing'10 upon an axis substantially perpendicular to that of shaft 13. A rack 22 (Figs. 4 and 5) is carried "by rod 12 and extends longitudinally along one side thereof. Shaft 13 has fixed thereto,.for rotation therewith, a pinion 23. A suitable gear train comprising'compound gears 24 and 25, establishes a driving connection between pinion 23 and rack 22 whereby rotation of shaft 13 will cause axial movement of push-rod 12.

Push-rod 12 projects through a'suita'ble bore in one end of casing 10 and thereon supports a circular shaped head member 26. Such member here comprises a base plate 27 normal to rod 12, such plate being faced on each side with a resilient material such as cork, sponge rubber, or the like. Casing 10 is formed with a collar 28 surrounding the projecting end of push-rod 12 substantially concentric therewith.

A fluid container 29 (Figs. 2 and 3) is formed with a closed end 30 having an outlet port '31, and with an aperture 32 surrounded by an annular skirt 33 having an internal diameter substantiallyequalto the external diameter of collar 28. A piston 34 is reciprocably received in container 29 for longitudinal movement therein. A suitable sealing gasket 35 provides a fluid tight seal between piston 34 and the wall of container 29. Said container and its piston thus comprises a fixeddisplacement pump.

A series of bayonet pins 36 project radially from collar 28 and skirt 33 is formed-with a'corresponding series of bayonet slots 37 for reception of pins 36. Thus, by first telescopically sleeving skirt '33 on collar 28 and thereafter turning container 29 relative to collar 28, the container is locked against axial displacement from the collar. As a further safety feature -to prevent accidental separation of the container from the casing, I prefer to rovide a wedge-type latch 38 (Figs. 1 and 2) pivoted for oscillation on a pin 39 adjacent collar 28. The latch comprises a nose-piece 38' slig'htlylonger'than the distance between pin 39 and the periphery of collar 28 and an oppositely projecting finger release arm 38". Spring means 40 (Fig. 4) urges nose-piece 38 into wedging engagement with skirt 33 after its telescopic association with collar 28. Counter-rotation of skirt 33 to disengage bayonet pins 36 from slots 37 can be accomplished only after finger release 38" is depressed to'move nose-piece 38' out of engagement with skirt 33.

By so seating the container on casing 10, the piston 34 is brought into position to be driven, by the head 26, toward the outlet port 31 of the container. Upon axial movement of push-rod 12 toward container 29, member 26 engages piston 34 and moves it toward discharge port 31. Thus fluid in container 29 is forced out of the container through said discharge port, at a rate, and under a pressure, controlled and determined by means later to be described. When not in use, the head member 26 is seated solidly against casing 10 and the facing thereon acts as a gasket to prevent entrance of water, dirt, or the like, into the interior of the casing.

The spring motor 11 is so wound as to exert a driving force onthe push-rod 12 to move the same in the direction of container 29. To restrain such movement, I provide brake means 41. Such means comprises a drum member 42 fixedon shaft 13 for rotation there with. A coiled spring 43 is wrapped snugly about said member in the drivendirection of shaft 13. One end of spring 43 is anchored to casing "10 as at 44 and the other end 45 is free floatin'g. Thus, as drum member 42 moves clockwise, as viewed in Fig. 5, spring 43 will wind tightly about the drum and halt its rotation. Such structure presents the well known type of self-energizing spring brake. Disengagement of spring 43 can only be accomplished by moving spring end 45 against the direction of drum rotation of shaft 13. To this end, I provide a bar 46 mounted for reciprocatory movement in casing along a line substantially perpendicular to shaft 13. One end 47 of said bar is located adjacent drum member 42 and has a perforation therein through which spring end 45 projects. Thus, movement of bar 46 to the left, as viewed in Fig. 5, will loosen spring 43 upon member 42 to permit rotation of shaft 13. Movement of bar 46 to the right will permit the spring to tighten about member 42, as above described, to halt rotation of shaft 13.

To effect lefthand movement of bar 46, as above described, I provide a shaft 48 oscillably journalled in casing 10 upon an axis substantially parallel to that of shaft 13 near the opposite end 53 of bar 46. Shaft 48 projects through a wall of casing 10 and is provided with a control knob 49 (see Figs. 1, 2 and 4), and

a pointer 50 cooperable with an ON-OFF dial 51 cari 54 turned out of the plane of bar 46 in the direction of shaft 48.

Counter-clockwise rotation of shaft 48 (as viewed in Fig. 5) causes foot 52 to contact finger 54 to shift bar 46 to the left. Clockwise rotation of said shaft moves foot 52 out of contact with finger 54 to permit I spring end to shift bar 46 to the right.

Once bar 46 has been moved to its lefthand position, some means must be provided to retain it in that position. To this end, I provide a latch device indicated generally by the reference numeral 55 comprising a I leaf 56 pivoted intermediate its ends upon a pin 57 for oscillation about an axis substantially parallel with the axis of shaft 13. End 58 of said leaf, nearest shaft 13, is provided with a toe 59 turned out of the plane of leaf 56 to bear against bar 46. Bar 46 is provided with a dog 60 which latches behind toe 59 when bar 46 is moved to its lefthand position. Counter-clockwise movement of leaf 56 about pin 57 will move toe 59 out of latching engagement with dog 60 to free bar 46 for movement to the right.

A coiled spring 61 has one end fixed to a stud 62 in turn releasably fixed to casing 10 by a screw 63. The

other end 64, of said spring, engages end 58 of leaf 56 (as is clearly shown in Figs. 5 and 8) to urge toe 59 toward bar 46. Rotation of stud 62 is one direction or the other varies the tension on spring end 64,

in turn varying the force required to be exerted against the end 65 of leaf 56 to rock said leaf about the axis of pin 57 and disengage toe 59 from dog 60.

Lateral guidance of bar 46 is here accomplished by forming said bar with a slot 66 elongated in the direc-' As a safety feature, I prefer to provide means for' preventing movement of bar 46 to the left to disengage spring brake 43 fom drum 42, except when container 29 has its skirt 33 firmly seated on collar 28 and locked on bayonet pins 36. To this end, I provide a rod 68 having one end 69 projecting through the wall of casing 10 in contiguity with the periphery of collar 28, upon an axis substantially parallel with that of push-rod 12. The opposite end 70 of said rod is suitably supported in a bearing element 71 carried by casing 10 for axial reciprocation of rod 68. A latch element 72 is pivoted intermediate its ends to casing 10 upon a pin 73 for oscillation about an axis substantially parallel to that of pin 57. End 74, of element 72, projects into juxtaposition with bar 46. Said bar is further formed with a second dog 75 engageable by latch end 74 to lock bar 46 in its most righthand position, as viewed in Fig. 5. The opposite end 76 of element 72 is disposed in the path of end 70 of rod 68. A spring 77 engages element 72 to urge end 74 into latching engagement with dog 75. Movement to the left (as viewed in Fig. 5) of rod 68 will cause end 70 to engage latch end 76 and rock it about pin 73 to move end 74 out of latching engagement with dog 75.

Only when latch end 74 is so moved out of latching engagement with dog 75 can shaft 48 be rotated to shift bar 46 to the left to release brake means 41. Rod 68 is shifted to the left by the engagement of end 69 with the rim of skirt 33. A notch 78 is provided in the rim of skirt 33 and so positioned as to register with rod end 69 as the skirt is moved axially into telescopic engagement with collar 28. Subsequent rotation of the skirt on collar 28 causes the edge of notch 78 (see Fig. 2) to engage rod end 69 and cam the rod to the left, as viewed in Figs. 2 and 5, thereby rocking latch element 72 about pin 73 and moving end 74 out of latching engagement with dog 75.

Preferably, the end 69 of rod 68 is largely buried in a groove 28' in the periphery of collar 28, and is guarded by a pin 28" located within said groove. Said pin projects substantially into the cylinder defined by the periphery of the collar, leaving only a thin segment of the rod end unguarded for operative engagement by the sleeve 33 while quite effectively guarding the rod against accidental shifting.

From the discharge port 31 of liquid container 29, conduit means, here in the form of a flexible tubing 79, leads to one end of a short piece of substantially rigid conduit 80 (Figs. 1, 2, 5, 6 and 10). A pillow block 81 is fixed to casing 10 and conduit 80 is removably fixed to said block by means of a spring clip 82 pivoted on a pin 83 carried by block 81, as seen in Fig. 10. A short length of resilient tubing 84 (Fig. 6) is fixed to the other end of conduit 80. By pinching tubing 84 a metering of the flow of liquid from container 29 is accomplished. The degree of the constriction formed by such pinching determines the rate of fiow of the liquid, and controls the rate at which rod 12 is driven by motor spring 16.

To effect such pinching of tube length 84, I provide a saddle shaped element 85 (Figs. 6 and 7) partially embracing a section of tube 84. A leaf 86 supports saddle 85 and a pin 87 supports leaf 86, at a point remote from the saddle, on casing 10 for the swinging of the saddle about the axis of pin 87. A strai ht spring wire 87' passes diametrically through pin 87 and is flexed, and fixed, to casing 10 in a direction to urge saddle 85 away from tubing 84.

An adjustment screw 88 is suitably mounted on casing 10 upon an axis substantially perpendicular to that of pm 87 and one end of said screw abuts the saddle 85. The other end of screw 88 carries a control knob 89 and a pointer 90 cooperating with an indicator plate 91 carried by casing 10. Plate 91 bears a time scale calibrated in minutes. Axial adjustment of screw 88 will vary the time required to discharge the liquid from the container, as will later become apparent.

An anvil 92 (see Fig. 7) comprises a hard spherical member 93 engaging tubing 84 opposite saddle 85 and bearing against said tubing to form a constriction 94 therein. The anvil is supported on a plate 95 carried by casing 10 for sliding movement along a line substantially parallel to the axis of screw 88. A coiled spring 96 (see Fig. 10) is seated in a socket 97 in casing 10. One end 98 (Fig. 6) engages plate 95 and the other end 99 engages in a radial slot in a Welsh plug 101 clamped in socket 97 to hold said end in a fixed position after the required torque is imposed on spring 96. Thus spring 96 urges plate 95 and anvil 92 into operative association with saddle 85. Initial adjustment of the rate of fluid flow is accomplished first by the adjustment of the tension of spring 96. Subsequent adjustments are then made by manipulation of screw 88.

To permit the insertion and removal of tubing 84 from between saddle 85 and anvil 92, it is necessary to move plate 95 to its leftmost position, as viewed in Fig. 7. For this purpose, I form plate 95 with a slot 102 elongated in the direction of plate travel (see Fig. 6). A threaded post 103 is mounted in casing 10 and passes through slot 102. Said post projects outside casing 10 and there carries a control knob 104 which, in the position of Fig. 7, bears against plate 95' to clamp plate 95 in place. A dog in the form of a pin 105 is carried on post 103. Plate 95 is further formed with a tab 106 turned out of the plane of said plate on the end of slot 102 remote from anvil 92 and into the path of dog 105 as the post is turned counter-clockwise as seen in Fig. 6.

At the same time, the post moves axially to relieve plate 95 of clamping pressure. Such movementof the dog will cause the dog to strike tab 106 and further rotation of post 103 will cam the dog against the tab to shift plate 95 to the left, as viewed in Fig. 7 (downward as viewed in Fig. 6). When post 103 reaches the limit of its counter-clockwise rotation, as viewed in Fig. 6, it will strike a stop surface 107 on casing 10, and in that position will hold plate 95, by engagement with tab 106, in its position most remote from saddle 85. That position is such as to allow easy removal or insertion of tubing 84 between saddle 85 and anvil 92 for a purpose later to become apparent.

The other end 108 of tubing 84 is sleeved on a nipple in a pressure control mechanism now to be described.

Casing is formed with a shallow circular well 109 (see Fig. 8) having a central port 110 therein. A cupshaped element 111 is seated in port 110 and, in turn, has a central aperture therein. A domed element 112 seats snugly in well 109 and is formed with an inlet port 113 (Figs. 5 and 6) and an outlet port 114 communicating with the interior of element 112 near the apex of element 112, as at 115, as most clearly seen in Fig. 8. A gasket 116 of resilient material is clamped between the rim of element 112 and the bottom of well 109. Preferably integrally formed with gasket 116 is a flexible, elastic diaphragm 117 peripherally supported on gasket 116 thereby defining a fluid tight, variable volume chamber 118, enterable only at 115. The diaphragm 117 is so proportioned and designed that when in equilibrium, it will lie substantially in a plane. Thus, as shown in Fig. 8, the diaphragm is in a condition of tension under the influence of the headed element 120.

A plunger 119 is reciprocably supported in a suitable bearing fixed in the central aperture in cup 111 and at its upper end carries a headed element 120 bearing against diaphragm 117. Resilient means 121, such as a ring of sponge rubber, or an equivalent sealing device such as a thin rubber bellows, is cemented between head 120 and the bottom of the cup 111 to form a flexible seal against intrusion of dirt or moisture into the internal 'mechanism when the domed element 112 is removed from housing 10.

The other end of plunger 119 bears against end 65 of latch leaf 56, the axis of plunger 119 being substantially perpendicular to pivot pin 57 (see Figs. 5 and 8). Thus downward movement of plunger 119 (the end thereof being in contact with end 65 of leaf 56) will rock leaf 56 about the axis of pin '57 to move toe 59 out of latching engagement with dog 60, freeing bar 46 for movement to the right (Fig. 5) to permit action of brake means 41.

The outlet port 114 of element 112 is provided with a nipple to which may be attached, for instance, a length of tubing 122 (Fig. 2) carrying a needle 123 for the intravenous injection of the liquid into a patients circulatory system.

The domed element 112 is removably held in the well 109 by means of a spring clip 124 (Fig. l) pivoted at one end to casing 10, as at 125, and latched to casing 10 at the other end, as at 126, for a purpose soon to become apparent.

Operation Control knob 49 is moved to its off position (see Fig. 2) to permit bar 46 to move to the right (see Fig. 5) to engage brake 41. Since no container has yet been attached to casing 10, rod 68 will be projected, permitting spring 77 (Fig. 5) to shift latch end 74 into latching engagement with dog 75. Control knob 14 is turned to move push-rod 12 to its extreme left hand position (see Fig. 5) thereby further winding spring 16.

To insure maximum sanitation, I prefer to provide, as a unitary part of my device, a container 29 connected through tubing 79 and rigid conduit 80 to the tubing 84 in turn connected to domed element 112 carrying gasket 116 and diaphragm 117 and connected to the needle 123 through tubing 122. Thus all parts in the path of the liquid from container 29 to the needle 123 are provided in one unit ready for use. As such, container 29 is telescopically associated with collar 28 by means of a skirt 33. Rotation of the skirt on the collar to lock container 29 to casing 10 shifts rod 68, as above described, moving end 74 of latch 72 out of latching engagement with dog 75.

Domed element 112 is seated in well 109 and fixed therein by clip 124. Tubing section 84 is placed between saddle and anvil 92 as tubing 80 is placed on pillow block 81 and fixed in place by clip 82. Control knob 89 is turned to place pointer 90 at off position (see Fig. 2) on scale 91; which is the setting for no discharge flow and moves saddle element 85 into calibrate position for supporting tube 84 (see Fig. 6) when anvil element 93 moves into set constricting engagement with tube 84. Control knob 104 is turned to move anvil element 93 into constricting engagement with tubing 84 under influence of spring and further turned to securely clamp bar (see Fig. 7) between plate 95 and casting 10. The mechanism is now ready for use. Control knob 89 is turned counter-clockwise its maximum movement to a fixed stop position. Control knob 49 is turned to the on position, thereby shifting bar 46 to release brake means 41 until fluid begins to flow from needle 123, and knob 49 is then returned to the off position, and control knob 89 is turned to set pointer 90 at off position on dial 91 (see Fig. 2). After inserting and securing the needle in patients vein, control knob 49 is again turned to on position, after which control knob 89 is turned to place pointer 90 at the graduation figure on scale 91 indicating the required rate of fluid flow as measured in minutes for a complete discharge of container 29. Liquid is forced out of the container 29 by the pressure of head 26 against piston 34. The rate of flow is, as said before, determined by the degree of constriction in tubing 84. Pressure within the line beyond the constrictor device acts against diaphragm 117 at all times. Should the pressure exceed a predetermined maximum controlled by the tension on spring 61, plunger 119 will be moved immediately downward (see Fig. 8) by diaphragm 117 rocking latch leaf 56 about the axis of pin 57 to disengage toe 59 from dog 60. Such excessive pressure may arise, for instance, if the egress port of the needle is accidentally dislodged from the vein and intramuscular infiltration begins. Bar 46 is thus freed, to be moved to the right (see Fig. 5) by spring end 45, permitting the brake means to be energized, and halting the advancement of the piston 34 toward the container discharge port. As is clearly shown in Fig. 5, the dog 60 is so formed that, as it moves toward the right past toe 59, it will cam that toe upwardly to swing the end 65 of leaf 56 out of supporting relation with plunger 119. Diaphragm 117 will thus be permitted to contract to enlarge the chamber 118 to create a slight negative pressure in the tube length 79, thus tending to withdraw any liquid which may have infiltrated intramuscularly.

When the injection has been completed (and whether or not the container has been completely emptied) the control knob 49 will be turned to 01f position. Thereby, the foot 52 will be swung to engage and shift the finger 67 toward the right, as viewed in Fig. 5, thus swinging the latch device 55 counter-clockwise to release the engagement of the toe 59 with the dog 60.

At the end of the liquid-discharging cycle, of course, the push rod 12 maybe retracted by manual rotation of the finger piece 14.

Additionally, I prefer to provide an indicator dial 127 (Figs. 2 and 4) having a pointer 128 mounted on a shaft 129 and driven by a gear 130 in mesh with compound gear 25, for the purpose of showing, at any time, the quantity of liquid which has been discharged from container 29.

By the use of my device, intravenous injection of liquid can be accomplished under conditions which would render such therapy impossible using the conventional elevated container methods. The device is trustworthy, durable, and contains features intended to insure maximum safety during such a procedure. By its use, it is believed many patients may be saved who would otherwise become fatalities due to delay in obtaining needed treatment.

It will be clear that my device as disclosed herein may be used for discharging other fluids in other procedures, though I presently believe that its primary utility is in the administration of intravenous injections.

I claim as my invention:

1. Liquid metering mechanism comprising a length of collapsible tubing, a saddle element engaging a section of said tubing, an anvil engaging said tubing section opposite said saddle element to form a constriction therein, a leaf supporting said saddle element, a pin supporting said leaf at a point remote from said saddle element for swinging movement of said saddle element about the axis of said pin toward and away from said anvil, and screw means bearing against said saddle element upon an axis substantially perpendicular to the axis of said pin, said screw means being axially adjustable to alter the degree of constriction in said tubing.

2. Liquid metering mechanism comprising a length of collapsible tubing, a saddle element engaging a section of said tubing, an anvil engaging said tubing section opposite said saddle element to form a constriction therein, a leaf supporting said saddle element, a pin fixed to and supporting said leaf at a point remote from said saddle element for swinging movement of said saddle element about the axis of said pin toward and away from said anvil, screw means bearing against said saddle element upon an axis substantially perpendicular to the axis of said pin, said screw means being axially adjustable to alter the degree of constriction in said tubing, and resilient means operatively associated with said saddle element to bias said saddle element against said screw means.

3. The mechanism of claim 1 including a plate supporting said anvil and guided for movement along a line substantially parallel with the axis of said screw means and substantially in the plane of said leaf, such movement of said plate being between a position in which said anvil is in operative association with said saddle element and a position in which said anvil is out of operative association with said saddle element, resilient means engaging said plate to urge it toward its first said position, and control means cooperable with said plate for movement of said plate from its first said position and to hold it in its second said position.

4. The mechanism of claim 3 in which said plate is formed to provide a slot elongated in the direction of plate movement and with a tab turned out of the plane of said plate substantially at right angles thereto at the end of said slot remote from said anvil, said control means comprising a post passing through said slot and journalled for oscillation upon an axis substantially perpendicular to said plate, said post having a radially projecting dog, said dog and said tab lying substantially in a common plane parallel with said plate, said dog, upon rotation of said post, striking said tab to cam said plate from its first said position and to hold it in its second said position.

5. The device of claim I in which said anvil is formed to present a convex, substantially spherical surface for engagement with said tubing section.

6. A fluid motor comprising a base, a domed element fixed to said base and formed to provide an inlet port and an outlet port communicating with the interior of said element, an elastic diaphragm stretched between said base and said element to define, with said element, a fluidtight, variable-volume chamber closed except for said inlet and outlet ports, a plunger mounted for reciprocation along an axis substantially coaxial with said element with one end thereof abutting the outer surface of said dia- I phragm, and means resiliently urging said plunger to flex said diaphragm in a direction to ensmall said chamber.

7. Pressure responsive mechanism comprising a base, a domed element removably fixed to said base and formed to provide an inlet port and an outlet port near the apex thereof communicating with the interior of said domed element, an annular gasket confined between the rim of said domed element and said base, a flexible diaphragm peripherally fixed to said gasket to define, with said element, a fluid-tight, variable-volume chamber closed except for said inlet and outlet ports, a plunger having a headed end engaging the outer surface of said diaphragm, axial bearing means mounting said plunger for axial reciprocation substantially upon the axis of said domed element, and a ring of resilient material surrounding said plunger and confined between said base and the headed end of said plunger to seal the axial bearing of said headed plunger from intrusion of dirt and moisture.

8. in a device of the class described, a casing supporting motor means, an axially reciprocable push-rod mounted in said casing, means drivingly connecting said motor means to said push-rod, a liquid container having a discharge port and a piston axially movable in said container toward said discharge port, said container being secured to said casing substantially coaxially with said push-rod with one end of said rod abutting said piston, brake means. operatively engageable with said motor means to prevent movement of said push-rod in one direction under certain conditions, liquid flow-rate controlling means, conduit means connected to conduct fluid from the container discharge port to said flow-rate controlling means, pressure-responsive means, conduit means connected to conduct fluid from said flow-rate controlling means to said pressure-responsive means, and brake controlling means operable by said pressure-responsive means to release said brake means for movement thereof into braking engagement with said motor means when the liquid pressure in said pressure-responsive means reaches a predetermined maximum.

9. A liquid dispensing instrument comprising a mechanism housing enclosing a spring motor, a self-energizing brake arranged to prevent operation of said motor, when engaged, a slidable push rod, and rack-and-pinion means connecting said motor to drive said push rod, a fixeddisplacement pump comprising a liquid container cylinder removably attached to said housing and a piston in said cylinder engageable by said push rod when said cylinder is so attached to said housing, a discharge tube leading from said cylinder and having a compressible section, pinching mechanism carried by said housing and engageable with said tube section, a unit providing a variable-volume chamber having one wall defined by an elastic diaphragm, said chamber being connected in said discharge tube beyond said compressible section and said unit being attachable on said housing, and means connecting said diaphragm to effect engagement of said brake upon an increase of fluid pressure in said chamber beyond a predetermined value.

10. The liquid dispensing instrument of claim 9 including means for manual control of said brake comprising a shaft journalled in said housing, a dial knob fixed on said shaft, a cam lever fixed on said shaft, a slidable member engaging said brake and movable in one direction to release said brake, said cam lever being movable in one direction to engage said slidable member to move the same in said one direction, and a pivoted latch device resiliently biased for latching engagement with said slidable member upon movement thereof in said one direction, said cam lever, upon movement in the opposite direction, engaging a portion of said latch device to shift the latter out of engagement with said slidable member.

11. The device of claim 8 in which said motor means comprises a barrel supported in said casing, a shaft coaxial with said barrel, and a coiled spring having one end fixed to said barrel and the other end drivingly connected to said shaft, said means drivingly connecting said motor means to said push-rod comprising a pinion fixed to said shaft, a rack fixed to said push-rod and extending axially thereof, and a gear train drivingly connecting said pinion to said rack.

12. The device of claim 11 in which said barrel is journalled for rotation on said shaft whereby the barrel may be rotated to wind the spring therein, and including oneway brake means carried by said casing and engageable with said barrel to prevent the subsequent unwinding of said spring by counter-rotation of said barrel.

13. The device'of claim 11 in which said pressureresponsive means comprises a domed element removably fixed to said casing and formed to provide an inlet port, connected by a conduit with said liquid flow-rate controlling means, and an outlet port, both said ports communicating with the interior of said domed element near the apex thereof, an annular gasket confined between the rim of said domed element and said casing, a flexible diaphragm peripherally fixed to said gasket to define, with said domed element, a fluid-tight, variable-volume chamber closed except for said inlet and outlet ports, a plunger having a headed end engaging the outer surface of said diaphragm, said plunger being mounted for axial reciprocation substantially upon the axis of said domed element, and resilient means acting on the other end of said headed plunger, through said brake controlling means, to yieldably hold said headed plunger end in engagement with said diaphragm.

14. The device of claim 13 in which the shaft of said motor means is provided with an enlarged drum element fixed thereon for rotation therewith and said brake means comprises a coiled spring wrapped snugly about said drum member in the direction of driven rotation of said shaft, one end of said spring being fixed relative to said casing, said brake controlling means comprising a bar guided for reciprocation in said casing along a line substantially perpendicular to the axis of said motor shaft and to the plunger of said pressure-responsive means, the other end of said coiled spring projecting radially from said drum member and being connected to said bar, a pin supported in said casing, a latch element pivoted substantially at its midpoint on said pin for oscillation about the axis thereof upon an axis substantially parallel to said motor shaft and perpendicular to the plunger axis of said pressureresponsive means, said other end of said plunger bearing against one arm of said latch, said latch element providing a toe on the other arm thereof turned out of the plane of said element toward said bar for engagement therewith, said bar being further provided with a dog engageable by said toe, when said bar is in its position farthest from said motor shaft, to lock said bar against movement toward said motor shaft, and spring means engaging said latch element to urge said toe into latching engagement with said dog.

15. The device of claim 14 including means for manually shifting said bar to its position farthest from said motor shaft to render said brake means inefiective upon said motor shaft, said means comprising a control shaft journalled for rotary movement upon an axis substantially parallel with said motor shaft adjacent said bar and carrying a radially projecting foot, said bar further providing a finger turned out of the plane of said bar toward said control shaft, said foot and said finger being so positioned that, upon rotation of said control shaft, said foot will contact said finger to so shift said bar.

16. The device of claim 14 in which said liquid container is removably fixed to said casing, said casing being externally formed to provide a collar substantially concentric with said push-rod and said container being formed on the end thereof remote from said discharge port with an annular skirt, said collar being telescopically receivable in said skirt annulus, means being provided for fixing said skirt annulus against accidental disassociation from said collar, said device further including safety means operable to permit operation of said motor means only when said container is securely fixed on said casing, such means comprising a rod carried by said casing for reciprocation upon an axis substantially parallel to said pushrod axis, one end of said rod projecting from said casing in contiguity with the periphery of said casing collar whereby the said end will be contacted and depressed by the rim of said skirt upon proper seating of said skirt on said collar, a further latch element, a pin pivotally supporting said further latch element intermediate its ends for oscillation about an axis substantially parallel with the pin axis of the first said latch element, said bar being further provided with a second dog, one end of said second latch element being engageable with said second dog to prevent movement of said bar in the direction away from said motor shaft, the other end of said rod abutting the other end of said second latch element, and spring means operatively engaging said second latch element to urge the first said end into latching engagement with the second said dog.

17. In a device of the class described, a casing, a spring motor in said casing, a push rod reciprocably mounted in said casing and projectible therefrom, means operatively connecting said motor to drive said rod outwardly relative to said casing, a fluid container having a discharge port adjacent one end thereof, cooperative means on said casing and container securing said container to said casing with the other end of said container in registry with the projectible end of said push rod, a movable wall member closing said other end of said container and being positioned, when said container is so secured, for operative engagement by said push rod, brake means operatively associated with said motor, means for rendering said brake means ineffective, and latch means normally preventing actuation of said last-named means to render said brake means ineffective.

18. The device of claim 17 including a member shiftable to release said latch means, said member having a portion normally lying in the path of association of said container with said casing whereby said member is engaged by said container as said container is secured to said casing and is so shifted to release said latch means.

19. In a device of the class described,a casing, a spring motor in said casing, a push rod reciprocably mounted in said casing and projectible therefrom, means operatively connecting said motor to drive said rod outwardly relative to said casing, a fluid container having a discharge port adjacent one end thereof, cooperative means on said casing and container securing said container to said casing with the other end of said container in registry with the projectible end of said push rod, a movable wall member closing said other end of said container and being positioned, when said container is so secured, for operative engagement by said push rod, brake means operatively associated with said motor, means for rendering said brake means ineffective, and latch means engageable with said last-named means to hold the same in position rendering said brake means ineffective.

20. The device of claim 19 including conduit means connected with said discharge port to conduct fluid discharged from said container to a point of use, pressure responsive means connected in said conduit means, and an element shiftable by said pressure responsive means and operatively associated with said latch means to release the same upon impressment of a predetermined pressure value on said pressure responsive means.